A Convergent Synthesis of 14-Membered F-O-G Ring Analogs of the Teicoplanin Binding Pocket via Intramolecular SNAr Reaction

An intramol. SNAr reaction for efficient macrocyclization via biaryl ether formation was developed for syntheses of the 14-membered macrocycles I and II (R = NH2, NO2) related to F-O-G ring of teicoplanin. Chloride as well as fluoride could be used as the leaving group in this reaction. However, the latter was preferred since it required milder conditions. Both ortho and para nitro, fluoro disubstituted arom. rings were suitable for the macrocyclization reaction with tethered aryl oxides. The nonproteinogenic alpha -amino acid III, required for the synthesis of II, was prepd. via an asym. Strecker synthesis using (R)-phenylglycinol as a chiral auxiliary. The overall synthetic strategy was convergent, and the cyclization could be performed in the presence of the highly sensitive arylglycine unit without racemization. [on SciFinder (R)]